1. Field of the Invention
The present invention relates to an abnormality judgment apparatus and an abnormality judgment method of a liquid supply system, and more particularly to technology for judging abnormalities and identifying the location of abnormalities in a liquid supply system which supplies liquid from a liquid tank to a liquid ejection head via a liquid flow channel.
2. Description of the Related Art
An ink supply apparatus for supplying ink to a recording head (inkjet head) is generally provided in an inkjet recording apparatus. An ink supply apparatus mainly includes an ink tank which accommodates ink, an ink supply channel which connects the recording head with the ink tank, and a pump which is provided in the ink supply channel, and ink is supplied from the ink tank to the recording head via the ink supply channel in accordance with the driving of this pump.
If an abnormality occurs in the ink supply apparatus, not only does normal printing become impossible, but there is also the possibility of trouble such as leaking of the ink to the exterior of the apparatus.
In particular, in an inkjet recording apparatus having high productivity which is capable of printing printed items of large size at high speed, sufficient ink must be supplied at a high flow rate enough to be consumed by the recording head, and if there is trouble in the ink supply apparatus, then there is a possibility of a larger amount leaking outside the apparatus. Furthermore, in order to be able to restore conditions rapidly after the occurrence of an abnormality, it is necessary to be able rapidly to identify the location of an abnormality.
Therefore, in an inkjet recording apparatus, one major technical issue is to be able to rapidly detect abnormalities in respective devices of an ink supply apparatus, while ensuring stable printing, and thus preventing trouble such as ink leaks, in advance, as well as being able rapidly to identify the locations of abnormalities so as to be able to restore the apparatus swiftly in the event of an abnormality. Various technologies relating to ink supply have been proposed hitherto (see, for example, Japanese Patent Application Publication No. 7-205440, and Japanese Patent Application Publication No. 200-229422).
Japanese Patent Application Publication No. 7-205440 discloses technology which selectively activates a first halt control device which halts a supply of ink to a recording head and also supplies a solution and then halts operation, and a second halt control device which terminates ink supply to a recording head and immediately halts operation, to minimize soiling caused by leaking of ink, even if an abnormal state causing leaking of ink has occurred.
Japanese Patent Application Publication No. 2000-229422 describes technology whereby, if the number of revolutions of a motor lies outside a predetermined tolerable range when the ink pressure supplied to nozzles of a recording head matches a predetermined correct value, an abnormality is taken to have occurred in the components, such as a pump which conveys ink to the nozzles, a motor which drives the pump, a filter which is provided in the ink supply tube, or an ink supply channel which is disposed between the ink tank and the nozzle, and so on, and the inkjet recording apparatus is automatically halted.
However, in the technology described in Japanese Patent Application Publication No. 7-205440, there is no concrete description of the method of detecting abnormalities and it is not possible to identify the location of an abnormality.
The same applies to the technology described in Japanese Patent Application Publication No. 2000-229422, and it is not possible to judge whether the cause of an abnormality is due to a sensor, motor, flow channel leak or flow channel blockage.
In this way, in the related art technology, it is not possible to identify specifically the location of an abnormality occurring in the ink supply apparatus, and hence it is difficult to restore the ink supply apparatus rapidly after the occurrence of an abnormality.